Autograph on cards question

[anagle]

I am a newbie and would appreciate advice regarding autographs on cards. I am planning to attend a card show next weekend in Chicago and noticed that Montana, Jim Brown and Schmidt will be signing. I have each of their rookie cards - Montana PSA 8, Brown PSA 4 and Schmidt (not graded with crease probably PSA 2 or 3) - and am considering breaking the slabs, getting them signed and then submit to PSA.
First question - is this a good idea? does if increase or decrease the value of the card? I will have to pay about $200 autograph fees + grading/shipping fees to PSA. For the Montana, is it better to pickup a low grade card to get signed or would you crack the 8??? When submitting to PSA, would you also grade the card (red label) or autograph only??
IMO it would be cool to meet them in person and get their auto on their rookie card but I don't want to do anything that would devalue the card if in the future i try to sell. is there a market for autographed cards? Thanks in advance to anyone who takes the time to response.